The Hasegawa WAH-64D is a straight reissue of their AH-64D, and represents one of the first Longbows to enter into the Army Air Corps. Since then, the WAH-64D has been fitted with the Helicopter Integrated Defensive Aids System (HIDAS). The Revell Of Germany 1/48 AH/WAH-64D has all the bits to build a HIDAS'ed Longbow. You can pick that kit up at a fairly decent price and have the HIDAS bits for your Hasegawa Longbow, plus still build either an AH-64A or US Army AH-64D from the RoG kit.
As for good photo references;
http://www.airliners.net/search/photo.search There are around 30 pics of the WAH-64D in the photo database
HTH,